tandem
1. tan.dem \'tan-d*m\ n [L, at last, at length (taken to mean "lengthwise"), fr. tam so; akin to]OE tht that 1a1: a 2-seated carriage drawn by horses harnessed one before the other 1a2: a team so harnessed 1b: a vehicle having close-coupled pairs of axles 2: a group of two or more arranged one behind the other or used or acting i n conjunction 2. tandem av(or aj) : one after or behind another